Bufferbloat Test

Q: What does this bufferbloat test measure?

It compares your idle ping against your ping while download traffic fills the connection (loaded latency). The gap between the two is your bufferbloat grade.

Q: What is a good loaded latency result?

A ping increase under 20 ms under load is excellent, 20-50 ms is good, 50-150 ms will cause lag during heavy use, and 150+ ms is classic bufferbloat.

Q: How do I fix bufferbloat?

Enable Smart Queue Management (SQM, FQ-CoDel, or CAKE) on your router, cap router bandwidth at about 90-95% of your tested speeds, use Ethernet for latency-sensitive devices, and replace old ISP routers without modern queue management.

Measure your loaded latency - How much your ping rises while your connection is busy. This is the fastest way to detect bufferbloat, router queueing, and lag during downloads or uploads.

What Is Bufferbloat?

What is bufferbloat?

Bufferbloat is excess queueing delay that appears when oversized router buffers fill up during downloads or uploads. The connection stays fast on paper, but ping spikes and calls, games, and browsing lag whenever the line is busy. Because idle ping tests never fill the buffers, bufferbloat hides from ordinary speed tests - You need to measure loaded latency, your ping while the connection is saturated, to see it.

What does this bufferbloat test measure?

Idle Ping

Your baseline round-trip time when the connection is quiet. This is the latency most simple ping tests report.

Loaded Latency

Ping while download traffic fills the connection. Big increases over idle ping mean router or ISP queueing.

Bufferbloat Grade

The gap between idle ping and loaded latency. A small gap feels smooth; a large gap causes lag during normal household use.

What is a good loaded latency result?

Ping increase under load	Rating	What it means
Under 20 ms	Excellent	Gaming, calls, and browsing should stay responsive while downloads run.
20-50 ms	Good	Most households will feel fine, though competitive gaming may notice small spikes.
50-150 ms	Fair	Video calls and games may lag whenever another device uses heavy bandwidth.
150+ ms	Poor	Classic bufferbloat: the connection is fast, but latency collapses under load.

How do I fix bufferbloat?

Enable Smart Queue Management, SQM, FQ-CoDel, or CAKE in your router if available.
Set router bandwidth limits to about 90-95% of your real tested download and upload speed.
Use Ethernet for latency-sensitive devices like gaming PCs, consoles, and work machines.
Pause large downloads, cloud backup, and file sync during important calls or games.
Replace older ISP routers if they do not support modern queue management.

For deeper troubleshooting, read our guides to bufferbloat, lowering ping, and fixing ping spikes.